Actually I had a young QH gelding who I had living around our house on the lawn. He got so used to everything that people do, it was quite amazing. I rode him down to the nearest township as a 3yr old and he was bomb proof, lawn mowers, rubbish bins, traffic, nothing bothered him at all. Infact I was chainsawing firewood in the backyard, Comet was also in the back yard. I had to stop usinig the saw because the silly horse kept getting in the way - I nearly cut his **** nose off!
I think you just have to expose young horses to as much as possible but ultimatley you just have to suck it up and get out there with them and sometimes there is no easy way.
Below is a pic of my mare Phoenix and I in the shed. I polish stainless steel for a job, I use noisy power tools that sometimes throw sparks. I have music blaring as well but it is a real struggle to keep my girl out of my work shop!